Fittings are used as connectors in order to link fluid conductors with each other. Fittings generally include a tubular element, or nipple having two ends. The first nipple end has an outer surface designed to connect with a further connector. This connector can be a stand-alone connector or can be part of a port, such as a manifold. The second nipple end has an outer surface which fixedly retains a tubular shell that circumferentially surrounds this end.
The second end of the nipple has an end portion that is adapted to be inserted into a conduit. The surrounding shell, which is attached to the second end of the nipple, surrounds the conduit. The conduit, or course, is the fluid conductor that is used to transfer fluid from one location to another. Typically, this conduit is flexible so that the fluid can be transferred in multiple directions or angulations without the awkward bending of a rigid pipe. The construction of the conduit is dependent on the application. For example, a conduit used for a high-pressure application will be thicker than that for a low-pressure application. As another example, a conduit used for water application will have different material that one used for fuel. In order to attach the conduit to the fitting, the shell is inwardly deformed so that the intermediate conduit portion is compressed between the shell and the nipple.
Shells can be fixedly attached to the nipple by several methods. As is well known in the art, the inner axial end of the shell can be inwardly deformed, or crimped, onto the nipple so that it is compressively attached. An example of such an attachment is shown in U.S. Pat. No. 5,031,301 to Oetiker. Other methods include radially compressing an inwardly directed shoulder of the shell into an annular groove in the nipple. An example of such an attachment is shown in U.S. Pat. No. 4,498,691 to Cooke. Another method of affixing the shell to the nipple includes axially compressing an inwardly directed shoulder of the shell between two radially outwardly extending protuberant surfaces, such as annularly formed beads. An example of such an attachment is shown in U.S. Pat. No. 3,924,883 to Frank. The attachment methods differ depending on the style of the mating conduit. For each of these attachment methods, the nipple outer profile is specifically designed for receiving one style of shell. That is, the nipple and shell are designed to only mate with each other. If a fabricator of a connector is intending to assemble the connector with multiple conduit styles, then the fabricator has to stock all styles of both the nipple and the shell. Due to the multitude of conduit styles, the manufacturer of the connector has to produce all styles of both the nipple and the shell. It is a disadvantage for a fabricator to have to stock a variety of nipple and shell styles. The fabricator would prefer to stock only one style nipple that is compatible with the various shell styles. It is also disadvantageous for the manufacturer to produce a variety of nipple and shell styles. The manufacturer would prefer to make only one style nipple that is compatible with all shell styles.
As previously mentioned, the conduit design is dependent on a variety of factors, one of which is the pressure of the application. A conduit intended for a high-pressure application will be thicker than that for a low-pressure application. The inner diameter of both conduits is the same but the outer diameter will change. Since the inner diameter remains the same, the fitting nipple also is the same for both applications. Since the outer diameter changes, the size of the shell has to change. This presents a disadvantage as to the number of parts required for a line of conduit sizes since these conduits require the same size nipple but different sized shells.